Cyclic AMP appears to regulate sperm metabolism and motility, since after experimental elevation of cyclic AMP levels in sperm increased oxygen consumption and motility are observed. Adenylate cyclase activity in sperm is elevated during capacitation and after ejaculation; thus enhanced activity of this enzyme may be directly related to cyclic AMP mediated changes in sperm metabolism and motility. However, at this time the properties of sperm adenylate cyclase are poorly understood, the enzyme(s) has not been purified and metabolically significant activators have not been identified. In this project activation of sperm adenylate cyclase will be studied in intact sperm, adenylate cyclase will be purified from sperm, and the latter characterized. The properties of the purified enzyme will be related to adenylate cyclase in intact sperm. These studies, particularly, will include investigation of the role of divalent metal ions in enzymatic activity and activation. Parallel studies on the activation of adenylate cyclase in intact sperm, particularly during in vitro capacitation, may lead to identification of new regulatory factors, as well as continuation of the study of metal ions in activation. Finally, an inhibitor of adenylate cyclase, present in cytoplasmic droplets, will be characterized and studied. Thus research proposed here will develop basic data on the properties of adenylate cyclase and provide information on the biochemical events involved in regulation of adenylate cyclase during sperm development.